Arabic Shows As Questions Mark In Discoverer Dashbaord?

i'm facing a problem with the discovereri i added a 4 dashboards in english and its comming up nicely but when i added the arabic ones the column names i tried to change them to arabic it writes in arabic but when i save changed and close them anfd try to open the worksheet again the arabic name i just wrote turns into ???????????? does anyone have a solution to this problem?






Regards